[PATCH] D25332: [ARM] Reapply: Use __rt_div functions for divrem on Windows

[Martin Storsjö via llvm-commits]

mstorsjo created this revision.
mstorsjo added reviewers: compnerd, rovka.
mstorsjo added a subscriber: llvm-commits.
Herald added subscribers: rengolin, aemerson.

Reapplying r283383 after revert in r283442. The additional fix is a getting rid of a stray space in a function name, in the refactoring part of the commit.

This avoids falling back to calling out to the GCC rem functions (__moddi3, __umoddi3) when targeting Windows.

The __rt_div functions have flipped the two arguments compared to the __aeabi_divmod functions. To match MSVC, we emit a check for division by zero before actually calling the library function (even if the library function itself also might do the same check).

Not all calls to __rt_div functions for division are currently merged with calls to the same function with the same parameters for the remainder. This is more wasteful than a div + mls as before, but avoids calls to __moddi3.

This is reapplying https://reviews.llvm.org/D24076 with one additional typo fix.


https://reviews.llvm.org/D25332

Files:
  lib/Target/ARM/ARMISelLowering.cpp
  test/CodeGen/ARM/Windows/dbzchk.ll
  test/CodeGen/ARM/divmod-eabi.ll

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